With the widespread use of wireless communication devices such as smart phones, the smart phone can support an increasing number of applications and is becoming more and more powerful. The smart phone is developing in a diversified and personalized way, becoming indispensable electronic products in users' life. In the fourth generation (4G) mobile communication system, the wireless communication device generally adopts a single-antenna or dual-antenna radio frequency (RF) system architecture. Currently, in a new radio (NR) system of the fifth generation (5G) mobile communication system, requirements on supporting a four-antenna RF system architecture are proposed.